The present invention relates to a congestion control function of a device provided on a terminal communication path in a network system, such as the World Wide Web (WWW), for communicating data between a server device and a terminal.
With the widespread use of mobile terminals, there is an increasing demand for synchronization of data such as schedules between a plurality of terminals such as mobile phones and PCs. It is also expected that with the development of highly functional terminals, the demand for synchronization is further increased with respect to a large amount of contents such as photos and videos. The synchronization of these data is performed by a synchronization server through data synchronization process. However, the load on the data synchronization server is expected to increase sharply as the demand for data synchronization increases. Thus, it is necessary to have a congestion control function to protect the synchronization server from the concentration of requests in order to provide a stable service.
An example of a conventional congestion control function is disclosed in U.S. Pat. No. 7,239,609. This document proposes that a congestion control system is provided on a path between a Web server and a Web client to determine whether the request relayed to the Web server exceeds the estimated processing capacity of the Web server, and to respond to the Web client with the coupling regulation time that is controlled based on the estimated processing capacity of the Web server (in column 2, lines 48 to 59).